Assignment
So, you've written code or documentation and used the GPL for Copyright. That only frees the software. It doesn't defend it. Large companies break the law all the time, stealing free software and then selling it without the source. Good luck defending your code against these violations. To get some help, it's best to assign ownership of your software to a larger entity that actually has staff and lawyers to defend freedom. That organization may be the Free Software Foundation (FSF), or the Software Freedom Conservancy (SFC).
FSF prefers copyright assignment for works that are part of the GNU system, such as GCC (https://gcc.gnu.org/contribute.html). However apparently not all software that is dubbed "GNU" is FSF Copyrighted -- meaning some works are copyright by individual authors.
Assignment of copyright (to the FSF) is NOT automatic when you license a work under the GPL. It's something you have to do. Assignment is the second half of making software free because it makes it defensible. As copyright owner, you could always hire your own lawyer and spend your time battling infringement cases, but you probably don't want this burden.
Sadly, I don't believe the FSF is equipped to receive assignment of all GPL software. But the SFC may be better prepared to partner with smaller projects. SFC Executive Director Karen Sandler appealed for financial support (donations), describing how very important their work is at LibrePlanet 2015.
More info on Copyright Assignment to FSF:
- Brief explanation by Eben Moglen https://www.gnu.org/licenses/why-assign.html
- Longer description from 2014 https://www.fsf.org/bulletin/2014/spring/copyright-assignment-at-the-fsf
- Actual templates http://git.savannah.gnu.org/cgit/gnulib.git/tree/doc/Copyright
See Also
While researching this topic, I found an interesting compendium of public documents on foundations that manage free software projects. https://gitorious.org/floss-foundations